1. Field of the Invention
This invention relates to a zoom lens equipped with the image stabilizing function.
2. Related Background Art
Zoom lenses equipped with the image stabilizing function according to the prior art have included a zoom lens comprised of two or more lens units as disclosed in U.S. Pat. No. 5,270,857 wherein any lens units (particularly first and fourth lens units) are displaced across the optical axis for image stabilization to thereby correct the imaging state, and a zoom lens as disclosed in U.S. Pat. No. 5,040,881 wherein during zooming, only some lens groups in a fixed first lens unit are moved to thereby correct the imaging state.
The above-described prior art, however, presupposes that it is used in small cameras such as so-called compact cameras, and suffers from the following problems when it is utilized as the lens of a so-called single-lens reflex camera.
Firstly, if the construction of such prior art is intactly applied to a lens for a single-lens reflex camera, there will arise a problem that the back focal length generally required cannot be secured sufficiently. Further, the zoom lens of the construction shown in the above-described example of the prior art suffers from a disadvantage that a great zoom ratio cannot be secured, and it is impossible to make a zoom lens equipped with the image stabilizing function having a zoom ratio equal to that of zoom lenses commercially available as interchangeable lenses for single-lens reflex cameras.